Light emitting element and method of manufacturing the same

ABSTRACT

A method of manufacturing a light emitting element includes, sequentially (a) forming a first light reflecting layer having a convex shape; (b) forming a layered structure body by layering a first compound semiconductor layer, an active layer, and a second compound semiconductor layer; (c) forming, on the second surface of the second compound semiconductor layer, a second electrode and a second light reflecting layer formed from a multilayer film; (d) fixing the second light reflecting layer to a support substrate; (e) removing the substrate for manufacturing a light emitting element, and exposing the first surface of the first compound semiconductor layer and the first light reflecting layer; (f) etching the first surface of the first compound semiconductor layer; and (g) forming a first electrode on at least the etched first surface of the first compound semiconductor layer.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a division of U.S. patent application Ser. No.14/449,840, filed Aug. 1, 2014, which claims the benefit of JapanesePatent Application No. JP 2013-166571, filed Aug. 9, 2013, the entiredisclosures of which are hereby incorporated herein by reference.

BACKGROUND

The present disclosure relates to a light emitting element and a methodof manufacturing the same.

Surface-emitting laser elements (vertical resonator laser, VCSEL)configured from a nitride semiconductor are known from, for example,Japanese Unexamined Patent Application Publication No. 2010-123921. Thesurface-emitting laser element disclosed in the unexamined patentpublication is manufactured by forming a layered body of a nitridesemiconductor in which a second conductivity type layer, a lightemitting layer and a first conductivity type layer are layered on asubstrate, forming a first black reflector formed from a dielectricmultilayer film on a first conductivity type layer, forming a firstelectrode electrically connected to the first conductivity type layer onthe first black reflector, bonding the layered body to a supportsubstrate via the first black reflector and the first electrode,exposing the second conductivity type layer by removing the substratefrom the layered body, and forming a second electrode, and a secondblack reflector formed from a dielectric multilayer film and arranged tooppose the first black reflector on the surface in which the secondconductivity type layer is exposed.

Although the second conductivity type layer is exposed by removing apart or all of the substrate from the layered body, a laser lift offmethod, polishing, etching or the like are used for the removal of thesubstrate. Scattering of light by the surface of the second conductivitytype layer is suppressed to the lowest limit by mirror finishing theexposed surface of the second conductivity type layer based on achemical/mechanical polishing (CMP) method using a suitable polishingagent, an etching method using a suitable etchant, or the like. A secondelectrode and a second black reflector are formed in an arbitrary orderon the mirror finished surface of the second conductivity type layer.

SUMMARY

Incidentally, on the surface of the substrate, it is important toachieve uniformity in the lengths of the first black reflector in eachsurface-emitting laser element, the layered body, and the resonatorformed from the second black reflector (more specifically, the thicknessof the layered body). Therefore, it is important to suppress theoccurrence of variations, for example, in the removal amount of thesecond conductivity type layer based on a CMP method on the surface ofthe substrate. However, there is no mention in the unexamined patentpublication with respect to a means for suppressing the occurrence ofvariations in the removal amount of the second conductivity type layeron the surface of the substrate. There is a problem of the contactresistance between the second conductivity type layer and the secondelectrode easily rising when the second electrode is formed on themirror finished surface of the second conductivity type layer.

Accordingly, it is desirable to provide a light emitting element havinga configuration and a structure able to achieve uniformity in the lengthof a resonator, and a method of manufacturing the same. It is alsodesirable to provide a light emitting element having a configuration anda structure able to suppress a rise in the contact resistance between aGaN-based compound semiconductor layer and an electrode, and a method ofmanufacturing the same.

According to a first embodiment of the present disclosure, there isprovided a method of manufacturing a light emitting element including,sequentially, (a) forming a first light reflecting layer having a convexshape formed from a multilayer film on a substrate for manufacturing alight emitting element; (b) forming a layered structure body by layeringa first compound semiconductor layer formed from a GaN-based compoundsemiconductor, which has a first surface and a second surface opposingthe first surface, an active layer formed from a GaN-based compoundsemiconductor, which contacts the second surface of the first compoundsemiconductor layer, and a second compound semiconductor layer formedfrom a GaN-based compound semiconductor, which has a first surface and asecond surface opposing the first surface, and in which the firstsurface contacts the active layer on the substrate for manufacturing alight emitting element that includes the first light reflecting layer;(c) forming, on the second surface of the second compound semiconductorlayer, a second electrode and a second light reflecting layer formedfrom a multilayer film; (d) fixing the second light reflecting layer toa support substrate; (e) removing the substrate for manufacturing alight emitting element, and exposing the first surface of the firstcompound semiconductor layer and the first light reflecting layer; (f)etching the first surface of the first compound semiconductor layer; and(g) forming a first electrode on at least the etched first surface ofthe first compound semiconductor layer.

According to a second embodiment of the present disclosure, there isprovided a method of manufacturing a light emitting element including,sequentially, (a) forming a convexity formed from a material differentfrom a material that configures a first compound semiconductor layer ona substrate for manufacturing a light emitting element; (b) forming alayered structure body by layering a first compound semiconductor layerformed from a GaN-based compound semiconductor, which has a firstsurface and a second surface opposing the first surface, an active layerformed from a GaN-based compound semiconductor, which contacts thesecond surface of the first compound semiconductor layer, and a secondcompound semiconductor layer formed from a GaN-based compoundsemiconductor, which has a first surface and a second surface opposingthe first surface, and in which the first surface contacts the activelayer on the substrate for manufacturing a light emitting element thatincludes the convexity; (c) forming, on the second surface of the secondcompound semiconductor layer, a second electrode and a second lightreflecting layer formed from a multilayer film; (d) fixing the secondlight reflecting layer to a support substrate; (e) removing thesubstrate for manufacturing a light emitting element, and exposing thefirst surface of the first compound semiconductor layer and theconvexity; and (f) removing the convexity, forming a first lightreflecting layer formed from a multilayer film on at least a part of thefirst surface on the first compound semiconductor layer from which theconvexity is removed, and forming a first electrode on at least a partof the first surface of the first compound semiconductor layer on whichthe first electrode is to be formed. The first electrode may be formedafter the first light reflecting layer is formed, or the first lightreflecting layer may be formed after the first electrode is formed.

According to another embodiment of the present disclosure, there isprovided a light emitting element including (A) a layered structure bodyformed by layering a first compound semiconductor layer formed from aGaN-based compound semiconductor, which has a first surface and a secondsurface opposing the first surface, an active layer formed from aGaN-based compound semiconductor, which contacts the second surface ofthe first compound semiconductor layer, and a second compoundsemiconductor layer formed from a GaN-based compound semiconductor,which has a first surface and a second surface opposing the firstsurface, and in which the first surface contacts the active layer; (B) afirst electrode and a first light reflecting layer; and (C) a secondelectrode and a second light reflecting layer formed from a multi layerfilm formed on the second surface of the second compound semiconductorlayer, in which a concavity with a forward tapered side surface isformed on the first surface of the first compound semiconductor layer,the first light reflecting layer is formed on at least the concavity,and the first electrode is formed on at least the first surface of thefirst compound semiconductor layer.

In the method of manufacturing a light emitting element according to thefirst embodiment of the present disclosure, the substrate formanufacturing a light emitting element is removed in a state in whichthe first light reflecting layer is formed. In the method ofmanufacturing a light emitting element according to the secondembodiment of the disclosure, the substrate for manufacturing a lightemitting element is removed in a state in which a convexity is formed.When removing the substrate for manufacturing a light emitting element,since the first light reflecting layer or the convexity function as onetype of stopper, it is possible to suppress the occurrence of removalvariations in the substrate for manufacturing a light emitting elementon the surface of the substrate for manufacturing a light emittingelement, and further, the occurrence of thickness variations the firstcompound semiconductor layer, and possible to achieve uniformity in thelength of the resonator, it is possible to achieve stability in thecharacteristics of the obtained light emitting element. In the method ofmanufacturing a light emitting element according to the first embodimentof the present disclosure, since the first electrode is formed on atleast the etched first surface of the first compound semiconductor layerafter the exposed first compound semiconductor layer is etched, it ispossible to suppress a rise in the contact resistance between the firstcompound semiconductor layer and the first electrode. In the lightemitting element of the present disclosure, since the first lightreflecting layer is formed on a concavity in which the side surface hasa forward taper, it is possible to suppress disturbances in theformation of a multilayer film of a portion of the first lightreflecting layer formed on the side surface of the concavity and in thevicinity of the side surface that is the bottom surface of theconcavity. The effect described in the specification is merely anexample and the disclosure is not limited thereto, and there may beadditional effects.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B are both schematic partial end face views of a lightemitting element and a modification example of the light emittingelement of Embodiment 1;

FIG. 2 is a schematic partial end face view of a modification example ofthe light emitting element of Embodiment 1;

FIGS. 3A, 3B and 3C are schematic partial end face views of a layeredstructure body or the like for illustrating a method of manufacturing alight emitting element of Embodiment 1;

FIGS. 4A and 4B are schematic partial end face views of the layeredstructure body or the like for illustrating the method of manufacturinga light emitting element of Embodiment 1 continuing from FIG. 3C;

FIGS. 5A and 5B are schematic partial end face views of the layeredstructure body or the like for illustrating the method of manufacturinga light emitting element of Embodiment 1, continuing from FIG. 4B;

FIGS. 6A and 6B are both schematic partial end face views of a lightemitting element and a modification example thereof of Embodiment 2;

FIGS. 7A and 7B are both schematic partial end face views of amodification example of the light emitting element of Embodiment 2;

FIGS. 8A and 8B are both schematic partial end face views of amodification example of the light emitting element of Embodiment 2;

FIGS. 9A and 9B are both schematic partial end face views of amodification example of the light emitting element of Embodiment 2;

FIGS. 10A and 10B are both schematic partial end face views of amodification example of the light emitting element of Embodiment 2;

FIGS. 11A and 11B are both schematic partial end face views of amodification example of the light emitting element of Embodiment 2;

FIGS. 12A and 12B are both schematic partial end face views of amodification example of the light emitting element of Embodiment 2;

FIGS. 13A, 13B and 13C are schematic partial end face views of a layeredstructure body or the like for illustrating a method of manufacturing alight emitting element of Embodiment 2;

FIGS. 14A and 14B are schematic partial end face views of the layeredstructure body or the like for illustrating the method of manufacturinga light emitting element of Embodiment 2, continuing from FIG. 13C;

FIGS. 15A and 15B are schematic partial end face views of the layeredstructure body or the like for illustrating the method of manufacturinga light emitting element of Embodiment 2, continuing from FIG. 14B;

FIG. 16 is a schematic partial end face view of the layered structurebody or the like for illustrating the method of manufacturing a lightemitting element of Embodiment 2, continuing from FIG. 15B;

FIG. 17 is a schematic partial end face view of the light emittingelement of Embodiment 3 (modification example of Embodiment 1); and

FIG. 18 is a schematic partial end face view of the light emittingelement of Embodiment 3 (modification example of Embodiment 2).

DETAILED DESCRIPTION OF EMBODIMENTS

Below, although the present disclosure will be described based on theembodiments with reference to the diagrams, the disclosure is notlimited to the embodiments, and various numerical values or materialsare given as examples in the embodiments. The description will be givenin the following order.

1. Description Relating Generally to Method of Manufacturing LightEmitting Element According to First Embodiment and Second Embodiment ofDisclosure and Light Emitting Element of Disclosure

2. Embodiment 1 (Method of Manufacturing Light Emitting ElementAccording to First Embodiment of Disclosure)

3. Embodiment 2 (Method of Manufacturing Light Emitting ElementAccording to Second Embodiment of Disclosure, Light Emitting Element ofDisclosure)

4. Embodiment 3 (Modification of Embodiment 1 and Embodiment 2), Others

Description Relating Generally to Method of Manufacturing Light EmittingElement According to First Embodiment and Second Embodiment ofDisclosure, and Light Emitting Element of Disclosure

In the method of manufacturing a light emitting element according to thefirst embodiment or the second embodiment of the disclosure, it ispossible to perform exposure of the first surface of the first compoundsemiconductor layer and the first light reflecting layer or theconvexity in step (e) based on a chemical/mechanical polishing method(CMP method). First, removal of the substrate for manufacturing a lightemitting element is performed by a wet etching method using an alkalineaqueous solution, such as an aqueous solution of potassium hydroxide oran aqueous solution of sodium hydroxide, an ammonia solution+a hydrogenperoxide, a sulfuric acid solution+a hydrogen peroxide, a hydrochloricacid solution+hydrogen peroxide, a phosphoric acid solution+hydrogenperoxide, a dry etching method, a lift off method using a laser,mechanical polishing method or the like, or by a combination thereof, orthe thickness of the substrate for manufacturing a light emittingelement is thinned, then the first surface or the like of the firstcompound semiconductor layer is exposed by performing achemical/mechanical polishing method.

In the method of manufacturing a light emitting element according to thesecond embodiment of the disclosure including the preferred form, it ispossible to etch a part of the first surface of the first compoundsemiconductor layer on which the first electrode is to be formed beforeforming the first electrode on the first surface of the first compoundsemiconductor layer in step (f). In this case, the following proceduresare given as examples of the procedure of removal of the convexity,formation of the first light reflecting layer, etching of the firstcompound semiconductor layer, and formation of the first electrode instep (f).

(f-1) removal of the convexity, formation of the first light reflectinglayer, etching of the first compound semiconductor layer, formation ofthe first electrode

(f-2) removal of the convexity, etching of the first compoundsemiconductor layer, formation of the first light reflecting layer,formation of the first electrode

(f-3) removal of the convexity, etching of the first compoundsemiconductor layer, formation of the first electrode, formation of thefirst light reflecting layer

(f-4) etching of the first compound semiconductor layer, removal of theconvexity, formation of the first light reflecting layer, formation ofthe first electrode

(f-5) etching of the first compound semiconductor layer, removal of theconvexity, formation of the first electrode, formation of the firstlight reflecting layer

(f-6) etching of the first compound semiconductor layer, formation ofthe first electrode, removal of the convexity, formation of the firstlight reflecting layer

Furthermore, in the method of manufacturing a light emitting elementaccording to the first embodiment or the second embodiment of thedisclosure including the preferred form described above, it is possibleto etch the part of the first surface of the first compoundsemiconductor layer on which the first electrode is to be formed basedon a reactive ion etching method (RIE method). However, it is alsopossible to use a reactive ion beam etching (RIBE) method, an electroncyclotron resonance (ECR) etching method, an ion beam etching method, orthe like, instead of the reactive ion etching method. Embodiments of theetching gas include a fluorine-based gas, such as CF₄, a chlorine-basedgas, such as Cl₂, CCl₄, SiCl₄, and an iodine-based gas, such as HI. Theetching gas may be used singly, or may be mixed and used.

Furthermore, in the method of manufacturing a light emitting elementaccording to the second embodiment of the disclosure including thevarious preferred forms described above, the convexity formed in step(a) may adopt a form where the top surface is smaller than the bottomsurface.

In the method of manufacturing a light emitting element according to thefirst or second embodiments of the disclosure including the variouspreferred forms described above or the light emitting element of thedisclosure, it is possible to adopt a form where the area centroid ofthe second light reflecting layer is not present on a normal line withrespect to the first light reflecting layer passing through areacentroid of the first light reflecting layer.

In the method of manufacturing a light emitting element according to thefirst or second embodiment of the disclosure including the variouspreferred forms described above or the light emitting element of thedisclosure, it is possible to adopt a form where the area centroid ofthe active layer is not present on a normal line with respect to thefirst light reflecting layer passing through area centroid of the firstlight reflecting layer.

On the substrate for manufacturing a light emitting element on which thefirst light reflecting layer or the concavity is formed, when the firstcompound semiconductor layer is formed using horizontal growth using amethod in which epitaxial growth is caused in the horizontal direction,such as an epitaxial lateral overgrowth (ELO) method, if first compoundsemiconductor layers that are epitaxially grown from the edge portion ofthe first light reflecting layer or the convexity towards the centerportion of the first light reflecting layer or the convexities meet,there are cases in which numerous crystal defects occur in the meetingpart. If the meeting parts in which numerous crystal defects are presentare positioned at the center portion of the element region (describedlater), there is concern of an adverse influence being exerted on thecharacteristics of the light emitting element. It is possible toreliably suppress the occurrence an adverse influence on thecharacteristics of the light emitting element, by attaining a state inwhich the area centroid of the second light reflecting layer is notpresent on the normal line with respect to the first light reflectinglayer passing through the area centroid of the first light reflectinglayer, and a state in which the area centroid of the active layer is notpresent on the normal line with respect to the first light reflectinglayer passing through the area centroid of the first light reflectinglayer.

In the method of manufacturing a light emitting element according to thefirst or second embodiment of the disclosure including the variouspreferred forms described above, or the light emitting element of thedisclosure, it is possible use a configuration in which the first lightreflecting layer and the first electrode are in contact. Alternatively,it is possible to use a configuration in which the first lightreflecting layer and the first electrode are separated, that is, anoffset is provided, and the separation distance is within 1 mm. In thiscase, in the method of manufacturing a light emitting element accordingto the second embodiment of the disclosure, or the light emittingelement of the disclosure, it is possible to use a configuration inwhich the protrusion part of the first compound semiconductor layer ispresent between the first light reflecting layer and the firstelectrode. If the element region (described later) positioned in thefirst light reflecting layer and the first electrode are separated, acurrent flows across a long distance in the first compound semiconductorlayer. Therefore, it is preferable that the separation distance bewithin 1 mm in order to suppress the electrical resistance occurring inthe current path to be low.

In the method of manufacturing a light emitting element according to thefirst of second embodiment of the disclosure including the variouspreferred forms and configuration described above, or the light emittingelement of the disclosure, it is preferable that the distance from thefirst light reflecting layer to the second light reflecting layer be0.15 μm or more and 50 μm or less.

In the method of manufacturing a light emitting element according to thefirst or second embodiment of the disclosure including the variouspreferred forms described above, or the light emitting element of thedisclosure, it is possible use a configuration in which light generatedin the active layer is emitted to the outside via the first lightreflecting layer. In this case, it is desirable that S₁>S₂ be satisfied,where the area of a part of the first light reflecting layer thatcontacts the first surface of the first compound semiconductor layer(part of the first light reflecting layer opposing the second lightreflecting layer) is S₁, and the area of a part of the second lightreflecting layer opposing the second surface of the second compoundsemiconductor layer (part of the second light reflecting layer opposingthe first light reflecting layer) is S₂.

In a form in which the area centroid of the second light reflectinglayer is not present on the normal line with respect to the first lightreflecting layer passing through the area centroid of the first lightreflecting layer, and a form in which the area centroid of the activelayer is not present on the normal line with respect to the first lightreflecting layer passing through the area centroid of the first lightreflecting layer, it is desirable that S₃>S₄ be satisfied, where thearea of a part that configures the element region (described later), andis a part of the first light reflecting layer that contacts the firstsurface of the first compound semiconductor layer (part of the firstlight reflecting layer opposing the second light reflecting layer) isS₃, and the area of a part that configures the element region, and is apart of the second light reflecting layer opposing the second surface ofthe second compound semiconductor layer (part of the second lightreflecting layer opposing the first light reflecting layer) is S₄.

In the light emitting element of the disclosure including the variouspreferred forms and configuration described above, it is possible toattain a form in which the second light reflecting layer is fixed to thesupport substrate.

In the method of manufacturing a light emitting element according to thefirst or second embodiment of the disclosure including the variouspreferred forms and configuration described above, the value of thesurface roughness Ra of the part of the first surface of the firstcompound semiconductor layer (bottom surface of the concavity) thatcontacts the first light reflecting layer is 3×10⁻⁹ m or less, and thevalue of the surface roughness Ra of the part of the first surface ofthe first compound semiconductor layer on which the first electrode isformed exceeds the value of the surface roughness Ra of the part of thefirst surface of the first compound semiconductor layer (bottom surfaceof the concavity) that contacts the first light reflecting layer. Thesurface roughness Ra is stipulated by JIS B-610:2001. It is possible tomeasure the surface roughness Ra, more specifically, based onobservation based on AFM or cross-sectional TEM.

In the method of manufacturing a light emitting element according to thefirst or second embodiment of the disclosure including the variouspreferred forms and configuration described above, it is desirable that,R₂/R₁≦1 be satisfied, where the contact resistance value of the part ofthe first surface of the first compound semiconductor layer (bottomsurface of the concavity) that contacts the first light reflecting layeris R₁, and the contact resistance value of the part of the first surfaceof the first compound semiconductor layer on which the first electrodeis formed is R₂.

Examples of the arrangement state of the first light reflecting layerand first electrode on the first surface of the first compoundsemiconductor layer may include the state in which the first lightreflecting layer and the first electrode are in contact, or the state inwhich the first light reflecting layer and the first electrode areseparated, as described above. Examples may also include a state inwhich the first electrode is formed up to the edge portion of the firstlight reflecting layer, and a state in which the first light reflectinglayer is formed up to on the edge portion of the first electrode,according to the circumstances. In a case in which the first lightreflecting layer is formed up to on the edge portion of the firstelectrode, it is necessary that the first electrode have an openingportion with given size so that basic mode light of laser oscillation isabsorbed as little as possible. Since the size of the opening portionchanges according to wavelength of the basic mode or the opticalconfinement structure in the horizontal direction (in-plane direction ofthe first compound semiconductor layer), although not limited thereto,the size is preferably on the order of approximately several times theoscillation wavelength λ.

In the method of manufacturing a light emitting element according to thefirst or second embodiment of the disclosure including the variouspreferred forms and configurations described above, or the lightemitting element of the disclosure, it is possible to attain a state inwhich the first electrode is formed from a metal or an alloy, and thesecond electrode is formed from a transparent conductive material. Byconfiguring the second electrode from a transparent conductive material,it is possible for the current to spread in the horizontal direction(in-plane direction of the second compound semiconductor layer), andpossible to efficiently supply a current to the element region(described next). It is preferable that the second electrode be formedon the second surface of the second compound semiconductor layer, andthe second light reflecting layer be formed on the second electrode.

The term “element region” indicates a region in which a constrictedcurrent is introduced, or a region in which light is confined by adifference in refractive index or the like, or a region in which laseroscillation occurs in a region interposed between the first lightreflecting layer and the second light reflecting layer, or a regionpractically contributing to laser oscillation in a region interposedbetween the first light reflecting layer and the second light reflectinglayer.

The light emitting element may have a structure formed from asurface-emitting laser element (vertical resonator laser, VCSEL) thatemits light from the top surface of the first compound semiconductorlayer via the first light reflecting layer, or may have a structureformed from a surface-emitting laser element that emits light from thetop surface of the second compound semiconductor layer via the secondlight reflecting layer.

In the light emitting element of the disclosure including the variouspreferred forms and configuration described above and the method ofmanufacturing a light emitting element according to the first or secondembodiment of the disclosure including the various preferred forms andconfigurations described above (below, these may be collectivelyreferred to as simply “the disclosure”), it is, more specifically,possible for the layered structure body to have a structure formed froman AlGaInN-based compound semiconductor. Examples of the AlGaInN-basedcompound semiconductor, more specifically, include GaN, AlGaN, GaInN,and AlGaInN. These compound semiconductors may include boron (B) atoms,thallium (Tl) atoms, arsenic (As) atoms, phosphorus (P) atoms, andantimony (Sb) atoms as desired. It is desirable that the active layerhave a quantum well structure. More specifically, the active layer mayhas a single quantum well structure (QW structure), or may have amultiple quantum well structure (MQW structure). Although the activelayer having a quantum well structure includes a well layer and abarrier layer having a structure in which at least one layer is layered,examples of the combination of (compound semiconductor that configuresthe well layer, compound semiconductor that configures the barrierlayer) includes (In_(y)Ga_((1-y))N, GaN), (In_(y)Ga_((1-y))N,In_(z)Ga_((1-z))N) [where y>z], and (In_(y)Ga_((1-y))N, AlGaN). It ispossible to configure the first compound semiconductor layer from afirst conductive type (for example, n-type) compound semiconductor, andconfigure the second compound semiconductor layer from a secondconductive type (for example, p-type) compound semiconductor differentfrom the first conductive type. The first compound semiconductor layerand the second compound semiconductor layer are also referred to as afirst cladding layer and a second cladding layer. It is preferable thata current constriction structure be formed between the second electrodeand the second compound semiconductor layer. The first compoundsemiconductor layer and the second compound semiconductor layer may be asingle structure layer, may be a multi-layer structure layer, or may bea superlattice structure layer. Furthermore, it is also possible to usea layer including a composition gradient layer and a concentrationgradient layer.

In order to obtain a current constriction structure, a currentconstriction layer formed from an insulating material (for example,SiO₂, SiN, or Al₂O₃) may be formed between the second electrode and thesecond compound semiconductor layer, or a mesa structure may be formedby etching the second compound semiconductor layer with an RIE method,or the like, or a current constriction region may be formed by partiallyoxidizing a portion of the layer of the layered second compoundsemiconductor layer from the lateral direction, and a region withlowered conductivity may be formed by ion implantation of impurities inthe second compound semiconductor layer, or these may be combined, asappropriate. However, it is necessary that the second electrode beelectrically connected with the part of the second compoundsemiconductor layer in which a current flows due to currentconstriction.

Examples of the substrate for manufacturing a light emitting elementinclude a GaN substrate, a sapphire substrate, a GaAs substrate, an SiCsubstrate, an alumina substrate, a ZnS substrate, a ZnO substrate, anAlN substrate, an LiMgO substrate, an LiGaO₂ substrate, an MgAl₂O₄substrate, an InP substrate, and an Si substrate, and substrates onwhich an underlayer or a buffer layer is formed on the surface (mainsurface) of these substrates. In a case of forming a GaN-based compoundsemiconductor layer on the substrate, the using a GaN substrate ispreferable in light of a low density of defects. Although it is knownthat the polarity/non-polarity/semi-polarity and characteristics of theGaN substrate change according to the growth face, it is possible to useany of the main surfaces of the GaN substrate in forming the compoundsemiconductor layer. With respect to the main surface of thesesubstrates, depending on the crystal structure (for example, cubicalcrystal-type, hexagonal crystal, or the like), it is possible to use thecrystal orientation surfaces referred to by names such as the so-calledA plane, B plane, C plane, R plane, M plane, N plane and S plane, or asurface offset in a specified direction therefrom. Examples of themethod of forming the various compound semiconductor layers thatconfigure the light emitting element include a metal organic chemicalvapor deposition method (MOCVD method, MOVPE method), a molecular beamepitaxy method (MBE method), and a hydride vapor deposition method inwhich a halogen contributes to transportation or reaction.

Examples of the organogallium source gas in the MOCVD method includetrimethyl gallium (TMG) gas and triethyl gallium (TEG) GAS, and examplesof the nitrogen source gas include ammonia gas and hydrazine gas. In theformation of a GaN-based compound semiconductor layer having an n-typeconductivity type, for example, silicon (Si) may be added as an n-typeimpurity (n-type dopant), and in the formation of a GaN-based compoundsemiconductor layer having a p-type conductivity type, for example,magnesium (Mg) may be added as a p-type impurity (p-type dopant). In acase where the GaN-based compound semiconductor layer includes aluminum(Al) or indium (In) as a constituent atom, trimethylaluminum (TMA) gasmay be used as an Al source and trimethylindium (TMI) gas may be used asan In source. Monosilane gas (SiH4 gas) may be used as an Si source, andcyclopentadienylmagnesium gas, methylcyclopentadienyl magnesium, andbiscyclopentadienylmagnesioum (Cp₂Mg) may be used as an Mg source.Examples of the n-type impurity (n-type dopant) include Ge, Se, Sn, C,Te, S, O, Pd and Po, in addition to Si, and examples of the p-typeimpurity (p-type dopant) include Zn, Cd, Be, Ca, Ba, C, Hg, and Sr, inaddition to Mg.

Although the support substrate, for example, may be configured fromvarious substrates given as examples of the substrate for manufacturinga light emitting element, or it is possible to configure the supportsubstrate from an insulating substrate formed from AlN or the like, asemiconductor substrate formed from, Si, SiC, Ge or the like, a metallicsubstrate or an alloy substrate, it is preferable to use a substratehaving conductivity, or preferable to use a metallic substrate or alloysubstrate from the viewpoint of mechanical properties, elasticdeformation, plastic deformation, heat dissipation or the like. Examplesof the thickness of the support substrate, for example, may be 0.05 mmto 0.5 mm. Although examples of the method of fixing the second lightreflecting layer to the support substrate include existing methods, suchas a bonding method including a soldering method, room temperaturewelding method, bonding methods using adhesive tape, and bonding methodsusing wax bonding, it is desirable that a soldering method or a roomtemperature welding method be adopted from the viewpoint of ensuringconductivity. In a case of using a silicon semiconductor substrate,which is a conductive substrate, as the support substrate, it isdesirable that a method in which bonding is possible at low temperaturesof 400° C. or less be adopted in order to suppress warping due todifferences in the thermal expansion coefficients. In a case of using aGaN substrate as the support substrate, the boding temperature may be400° C. or more.

It is preferable that the first electrode have a single layer structureor a multilayer structure including at least one type of metal includingalloys selected from a group including, for example, gold (Au), silver(Ag), palladium (Pd), platinum (Pt), nickel (Ni), titanium (Ti),vanadium (V), tungsten (W), chromium (Cr), aluminum (Al), copper (Cu),zinc (Zn), tin (Sn) and indium (In). More specifically, examplesinclude, for example, TI/Au, Ti/Al, Ti/Al/Au, Ti/Pt/AU, Ni/Au, Ni/Au/Pt,Ni/Pt, Ni/Pt, Pd/Pt, and Ag/Pd. The further to the front of the “/” alayer is in the multilayer structure, the further the layer ispositioned to the active layer side. The same applies in the descriptionbelow. It is possible to form the film of the first electrode, forexample, with a PVD method, such as a vacuum deposition method or asputtering method.

Examples of the transparent conductive material that configures thesecond electrode include indium tin oxide (ITO, including Sn dopedIn₂O₃, crystalline ITO and amorphous ITO), indium zinc oxide (IZO), IFO(F doped In₂O₃), tin oxide (SnO₂), ATO (Sb doped SnO₂), FTO (F dopedSnO₂), and zinc oxide (including ZnO, Al doped ZnO and B doped ZnO).Alternatively, examples of the second electrode include transparentconductive films in which the mother layer is made from gallium oxide,titanium oxide, niobium oxide, nickel oxide or the like. However,although dependent on the arrangement state of the second lightreflecting layer and the second electrode, the material that configuresthe second electrode is not limited to transparent conductive materials,and it is possible to use metals, such as palladium (Pd), platinum (Pt),nickel (Ni), gold (Au), cobalt (Co) and rhodium (Rh). The secondelectrode may be from at least one type of these materials. It ispossible to form the film of the second electrode, for example, with aPVD method, such as a vacuum deposition method or a sputtering method.

A pad electrode may be formed on the first electrode or the secondelectrode in order to electrically connect an external electrode or acircuit. It is desirable that the pad electrode have a single layerstructure or a multilayer structure including at least one type of metalselected from a group including titanium (Ti), aluminum (Al), platinum(Pt), gold (Au), nickel (Ni) and palladium (Pd). Alternatively, it ispossible to configure the pad electrode with a multilayer structure,examples of which include a multilayer structure of Ti/Pt/Au, amultilayer structure of Ti/Au, a multilayer structure of Ti/Pd/Au, amultilayer structure of Ti/Ni/Au, or a multilayer structure ofTi/Ni/Au/Cr/Au. In a case of configuring the first electrode from an Aglayer or an Ag/Pd layer, it is preferable that a cover metal layerformed from, for example, Ni/TiW/Pd/TiW/Ni be formed on the surface ofthe first electrode, and, for example, a pad electrode formed from amultilayer structure of Ti/Ni/Au or a multilayer structure ofTi/Ni/Au/Cr/Au be formed on the cover metal layer.

The light reflecting layer (distributed Bragg reflector layer, DBRlayer) is composed of, for example, a semiconductor multilayer film or adielectric multilayer film. Examples of the dielectric material include,for example, oxides of Si, Mg, Al, Hf, Nb, Zr, Sc, Ta, Ga, Zn, Y, B, Tior the like, a nitride (for example, AlN, AlGaN, GaN, Bn, or the like)or a fluoride. More specifically, examples include SiO₂, TiO₂, Nb₂O₅,ZrO₂, Ta₂O₅, ZnO, Al₂O₃, HfO₂, and AlN. It is possible to obtain a lightreflecting layer by alternately layering two or more types of dielectricfilm formed from dielectric materials with different reflectivities fromamong these dielectric materials. For example, a multilayer film such asSiO₂/SiN, SiO₂/Nb₂O₅, SiO₂/ZrO₂ and SiO₂/AlN is preferable. In order toobtain the desired reflectivity, the material configuring eachdielectric film, the film thickness, the number of layers and the likemay be selected as appropriate. It is possible to adjust the thicknessof each dielectric film, as appropriate, according to the material used,and thickness is determined according to the oscillation wavelength λ,and the reflectivity n with the oscillation wavelength λ of the materialused. More specifically, it is preferable that the thickness be an oddnumber multiple of λ/(4n). For example, in a light emitting element withan oscillation wavelength λ of 410 nm, in a case of configuring thelight reflecting layer from SiO₂/Nb₂o₅, examples of the thicknessinclude approximately 40 nm to 70 nm. Examples of the number of layersare two or more, and preferably approximately 5 to 20. Examples of theoverall thickness of the light reflecting layer include, for example,approximately 0.6 μm to 1.7 μm.

Alternatively, it is desirable that the first light reflecting layerinclude a dielectric film including at least an N (nitrogen) atom, andit is more desirable that the dielectric layer including the N atom bethe uppermost layer of the dielectric multilayer film. Alternatively, itis desirable that the first light reflecting layer be covered by adielectric material layer including at least an N (nitrogen) atom.Alternatively, it is desirable that the surface of the first lightreflecting layer be made a layer including at least an N (nitrogen) atom(below, referred to as a “surface layer”, as a matter of convenience) bysubjecting the surface of the first light reflecting layer to anitriding treatment. The thickness of the dielectric film or thedielectric material layer including at least an N atom and the surfacelayer is preferably set to an odd numbered multiple of λ/(4n). Examplesof the material that configures the dielectric film or the dielectricmaterial layer including at least an N atoms specifically includeSiN_(y) and SiO_(x)N_(y). In this way, by forming the dielectric film ordielectric material layer including at least an N atom, and the surfacelayer, when the compound semiconductor layer that covers the first lightreflecting layer is formed, it is possible to reduce shifting of thecrystal axis of the compound semiconductor layer that covers the firstlight reflecting layer and the crystal axis of the substrate formanufacturing a light emitting element, and possible to improve thequality of the layered structure body that is a resonator.

The size and shape of the light reflecting layer is not particularlylimited, as long as the layer covers the element region. Examples of theplanar shape of the opening provided in the element region, the firstlight reflecting layer, the second light reflecting layer, and thecurrent constriction layer similarly include, specifically, a circle, anellipse, a rectangle, and a polygon (triangle, quadrangle, hexagon orthe like). Examples of the planar shape of the first electrode include aring shape. It is desirable that the planar shape of the openingprovided in the element region, the first light reflecting layer, thesecond light reflecting layer, and the current constriction layer, theplanar shape of the inside ring portion of the annular first electrode,and further the planar shape of the convexity described later be similarshapes. In the case of a circular shape, it is preferable that thediameter be approximately 2 μm to 70 μm.

It is possible for the light reflecting layer to be formed based on anexisting method, and specific examples include PVD methods, such as avacuum deposition method, a sputtering method, a reactive sputteringmethod, an ECR plasma sputtering method, a magnetron sputtering method,an ion beam assisted deposition method, an ion plating method, a laserablation method; various CVD methods; coating methods, such as a spraymethod, a spin coating method, and a dipping method; a method in whichtwo or more of these methods are combined; and a method combining thesemethods with one or more of any of a complete or partial pre-processing,irradiation of inactive gas (Ar, He, Xe or the like) or plasma,irradiation of oxygen gas, ozone gas and plasma, oxidation treatment(heat treatment), and exposure treatment.

Examples of the material that configures the convexity (mask layer forselective growth), include semiconductor oxides or semiconductornitrides such as SiO₂, SiN, SiON; Nb₂O₅, Ta₂O₅, ZrO₂, AlN, Al₂O₃; metalsor high melting point metals such as Ti, W, Ni, Au, and Pt or an alloyin which the composition of these metals is appropriately adjusted (forexample, TiW, TiWCr, TiWNi, NiCr, TiNiCr, or alloys of these alloys andAu, or of these alloys and Pt, or the like); high melting point metal(alloy) oxides; high melting point metal (alloy) nitrides; a multilayerstructure in which materials different from one another, metals, alloys,alloy oxides, alloy nitrides are combined (for example, a layeredstructure of, from below, a silicon oxide layer and a silicon nitridelayer); and a resist material. Examples of the method of forming theconvexity include physical vapor-phase growth methods (PVD method), suchas a sputtering method, or a chemical vapor-phase growth method (CVDmethod), and a combination of a coating method and a lithographytechnology or an etching technology. Removal of the convexity depends onthe material that configures the convexity, and a wet etching method maybe adopted, a dry etching method may be adopted, or an asking technologymay be used. The convexity may have a one dimensional arrangement, suchas a band-shape, or may have a two-dimensional arrangement having acurved shape (circle, ellipse or the like) that is dotted or scattered,or a combination of curves, a combination of cures and line segments, ora polygonal shape (triangle, quadrangle, hexagon or the like).

The side surface or exposed surface of the layered structure body may becovered with an insulating film. Forming the insulating film may beperformed based an existing method. It is preferable that the refractiveindex of the material that configures the insulating film be lower thanthe refractive index of the material that configures the layeredstructure body. Examples of the material that configures the insulatingfilm include a SiO_(x)-based material including SiO₂, SiN_(y)-basedmaterial, a SiO_(x)N_(y)-based material, Ta₂O₅, ZrO₂, AlN, Al₂O₃, andGa₂O₃, or an organic material, such as a polyimide resin. Examples ofthe method of forming the insulating film include PVD methods, such as avacuum deposition method or a sputtering method, or a CVD method, or thefilm may be formed based on a coating method.

Embodiment 1

Embodiment 1 relates to a method of manufacturing a light emittingelement according to the first embodiment of the disclosure.

The light emitting element obtained by the method of manufacturing alight emitting element of Embodiment 1 shown in the schematic partialend face view in FIG. 1A or the light emitting element of Embodiments 2to 3 described later includes (A) a layered structure body 20 formed bylayering a first compound semiconductor layer 21 formed from a GaN-basedcompound semiconductor, which has a first surface 21 a and a secondsurface 21 b opposing the first surface 21 a, an active layer (lightemitting layer) 23 formed from a GaN-based compound semiconductor, thatcontacts the second surface 21 b of the first compound semiconductorlayer 21, and a second compound semiconductor layer 22 formed from aGaN-based compound semiconductor, which has a first surface 22 a and asecond surface 22 b opposing the first surface 22 a, in which the firstsurface 22 a contacts the active layer 23; (B) a first electrode 31 anda first light reflecting layer 41; and (C) a second electrode 32 and asecond light reflecting layer 42 formed from a multi layer film formedon the second surface 22 b of the second compound semiconductor layer22.

In the light emitting element of Embodiment 1, or Embodiments 2 and 3described later, the first electrode 31 is formed on at least the firstsurface 21 a of the first compound semiconductor layer 21, and the firstlight reflecting layer 41 formed from a multilayer film is formed on thefirst surface 21 a of the first compound semiconductor layer 21.

The light emitting element of Embodiment 1, or Embodiments 2 and 3described later is specifically formed from a surface-emitting laserelement (vertical resonator laser, VCSEL) that emits light from the topsurface of the first compound semiconductor layer 21 via the first lightreflecting layer 41.

In the light emitting element of Embodiment 1, or Embodiments 2 and 3described later, the current constriction layer 24 formed from aninsulating material, such as SiO₂, is formed between the secondelectrode 32 and the second compound semiconductor layer 22. A circularopening 24A is formed in the current constriction layer 24, and thesecond compound semiconductor layer 22 is exposed in the bottom portionof the opening 24A. The second electrode 32 is formed from over thesecond surface 22 b of the second compound semiconductor layer 22 toover the current constriction layer 24, and the second light reflectinglayer 42 is formed on the second electrode 32. A pad electrode 33 forelectrically connecting an external electrode or a circuit is connectedon edge portion of the second electrode 32. In the light emittingelement of Embodiment 1, or Embodiment 2 described later, the planarshape of the element region is a circle, and the planar shape of theopening 24A provided in the first light reflecting layer 41, the secondlight reflecting layer 42, and the current constriction layer 24 is alsoa circle. Meanwhile, the planar shape of the first electrode 31 isannular (ring-like). Although the first light reflecting layer 41 andthe second light reflecting layer 42 has a multilayer structure, for thesake of simplicity in the drawings, the layers are depicted by onelayer. Forming the current constriction layer 24 may not be necessary.

In the light emitting element of Embodiment 1, the first lightreflecting layer 41 and the first electrode 31 are separated, that is,an offset is provided, and the separation distance is within 1 mm,specifically, for example, an average of 0.05 mm.

In the light emitting element of Embodiment 1, or Embodiments 2 and 3described later, the second light reflecting layer 42 is fixed based ona soldering method to the support substrate 26 formed from a siliconsemiconductor substrate via a bonding layer 25 formed from a solderlayer including a gold (Au) layer or a tin (Sn) layer.

In the light emitting element of Embodiment 1, or Embodiments 2 and 3described later, light generated in the active layer 23 is emitted tothe outside via the first light reflecting layer 41. S₁>S₂ is satisfied,where the area of a part of the first light reflecting layer 41 thatcontacts the first surface 21 a of the first compound semiconductorlayer 21 (part of the first light reflecting layer 41 opposing thesecond light reflecting layer 42) is S₁, and the area of a part of thesecond light reflecting layer 42 opposing the second surface of thesecond compound semiconductor layer 22 (part of the second lightreflecting layer 42 opposing the first light reflecting layer 41) is S₂.The distance from the first light reflecting layer 41 to the secondlight reflecting layer 42 is 0.15 μm or more and 50 μm or less, and,specifically, is, for example, 10 μm.

The first compound semiconductor layer 21 is formed from an n-GaN layer,the active layer 23 is formed from a quintuple multiple quantum wellstructure in which an In_(0.04)Ga_(0.96)N layer (barrier layer) and anIn_(0.16)Ga_(0.84)N layer (well layer) are layered, and the secondcompound semiconductor layer 22 is formed from a p-GaN layer. The firstelectrode 31 is formed from Ti/Pt/Au, the second electrode 32 is formedfrom a transparent conductive material, specifically, ITO, the padelectrode 33 is formed from Ti/Pd/Au, the first light reflecting layer41 and the second light reflecting layer 42 are formed from a layerstructure of an SiN layer and an SiO₂ layer (total number of layers ofdielectric film: 20 layers).

Below, the method of manufacturing a light emitting element ofEmbodiment 1 will be described with reference to FIGS. 3A, 3B, 3C, 4A,4B, 5A and 5B which are schematic partial end face views of a layeredstructure body.

Step-100

First, a first light reflecting layer 41 formed from a multilayer filmand having a convex shape is formed on the substrate for manufacturing alight emitting element 11. Specifically, a patterned first lightreflecting layer 41 formed from a multilayer film is formed based on anexisting method, on the substrate for manufacturing a light emittingelement 11 formed from a GaN substrate. In this way, it is possible toobtain the structure shown in FIG. 3A. The shape of the first lightreflecting layer 41 is a disk-shape. However, the shape of the firstlight reflecting layer 41 is not limited thereto.

Step-110

Next, a layered structure body 20 in which a first compoundsemiconductor layer 21 formed from a GaN-based compound semiconductor,which has a first surface 21 a and a second surface 21 b opposing thefirst surface 21 a, an active layer 23 formed from a GaN-based compoundsemiconductor, that contacts the second surface 21 b of the firstcompound semiconductor layer 21, and a second compound semiconductorlayer 22 formed from a GaN-based compound semiconductor, which has afirst surface 22 a and a second surface 22 b opposing the first surface22 a, and in which the first surface 22 a contacts the active layer 23are layered is formed on the substrate for manufacturing a lightemitting element 11 including the first light reflecting layer 41.Specifically, it is possible to obtain a layered structure body 20 byforming the first compound semiconductor layer 21 formed from n-GaN bylateral direction growth using a method that causes epitaxial growth inthe lateral direction, such as an ELO method, and forming the activelayer 23 and the second compound semiconductor layer 22 thereupon, basedon an epitaxial growth method. Then, the current constriction layer 24having an opening 24A is formed based on an existing method, on thesecond surface 22 b of the second compound semiconductor layer 22 (referto FIG. 3B).

Step-120

Thereafter, the second electrode 32 and the second light reflectinglayer 42 formed from a multilayer film are formed on the second surface22 b of the second compound semiconductor layer 22. Specifically, forexample, the second electrode 32 is formed from over the second surface22 b of the second compound semiconductor layer 22 to over the currentconstriction layer 24 based on a lift-off method and the pad electrode33 is further formed from over the second electrode 32 to over thecurrent constriction layer 24 based on an existing method. In this way,it is possible to obtain the structure shown in FIG. 3C. Thereafter, thesecond light reflecting layer 42 is formed from over the secondelectrode 32 to over the pad electrode 33 based on an existing method.In this way, it is possible to obtain the structure shown in FIG. 4A.

Step-130

Thereafter, the second light reflecting layer 42 is fixed to the supportsubstrate 26 via a bonding layer 25. In this way, it is possible toobtain the structure shown in FIG. 4B.

Step-140

Next, the substrate for manufacturing a light emitting element 11 isremoved, and the first surface 21 a of the first compound semiconductorlayer 21 and the first light reflecting layer 41 are exposed.Specifically, first the thickness of the substrate for manufacturing alight emitting element 11 is thinned based on a mechanical polishingmethod, then the remainder of the substrate for manufacturing a lightemitting element 11 is removed based on a CMP method. In this way, thefirst surface 21 a of the first compound semiconductor layer 21 and thefirst light reflecting layer 41 are exposed, and it is possible toobtain the structure shown in FIG. 5A.

Step-150

Thereafter, the first surface 21 a of the first compound semiconductorlayer 21 is etched. Specifically the exposed first surface 21 a of thefirst compound semiconductor layer 21 is etched based on an RIE method(refer to FIG. 5B). Thereby, a rough surface region 21A is formed on thefirst surface 21 a of the first compound semiconductor layer 21.

Step-160

Next, the first electrode 31 is formed on at least the etched firstsurface 21 a of the first compound semiconductor layer 21. Specifically,the first electrode 31 is formed on the etched first surface 21 a of thefirst compound semiconductor layer 21 (on the rough surface region 21A)based on an existing method. In this way, it is possible to obtain thelight emitting element of Embodiment 1 having the structure shown inFIG. 1A.

Here, the value of the surface roughness Ra of the surface of the firstcompound semiconductor layer 21 in the interface between the first lightreflecting layer 41 and the first surface 21 a of the first compoundsemiconductor layer 21 (below, referred to as a “flat surface 21B”, as amatter of convenience) is 3×10⁻⁹ m or less, and the value of the surfaceroughness Ra of the rough surface region 21A exceeds the value of thesurface roughness Ra of the flat surface 21B. Specifically, the value ofthe surface roughness Ra of the flat surface 21B is 0.2 nm, and thevalue of the surface roughness Ra of the rough surface region 21A is 3.1nm.

R₂/R₁≦1 is satisfied, where the contact resistance value in the flatsurface 21B is R₁ and the contact resistance value in the rough surfaceregion 21A is R₂. Specifically, the IV curve in the flat surface 21B isa Schottky-type, and the IV curve in the rough surface region 21A is anohmic-type.

Step-170

Thereafter, the light emitting element is separated by performingso-called element separation, and the exposed surface of the sidesurface of the layered structure body is covered with an insulating filmformed from, for example, SiO₂. Thereafter, a terminal or the like forconnecting the first electrode 31 and the pad electrode 33 to anexternal circuit or the like is formed based on an existing method, andthe light emitting element of Embodiment 1 is completed by packaging orsealing.

In the method of manufacturing a light emitting element of Embodiment 1,the substrate for manufacturing a light emitting element is removed in astate in which the first light reflecting layer is formed. Therefore,the first light reflecting layer functions as one type of stopper whenremoving the substrate for manufacturing a light emitting element, it ispossible to suppress the occurrence of variations in the removal of thesubstrate for manufacturing a light emitting element on the surface ofthe substrate for manufacturing a light emitting element, and, further,variations in the thickness of the first compound semiconductor layer,and it is possible to attain results enabling achievement of uniformityin the length of the resonator and stability in the characteristics ofthe obtained light emitting element. Because the surface (flat surface)of the first compound semiconductor layer in the interface between thefirst light reflecting layer and the first compound semiconductor layeris flat, it is possible to suppress scattering of light by the flatsurface to a minimal level. Since the first electrode is formed on therough surface region, it is possible to suppress a rise in the contactresistance between the first compound semiconductor layer and the firstelectrode.

In the example of the light emitting element described above and shownin FIG. 1A, the end portion of the first electrode 31 is separated fromthe first light reflecting layer 41. Meanwhile, in the example of thelight emitting element shown in FIG. 1B, the end portion of the firstelectrode 31 contacts the first light reflecting layer 41.

In the example of the light emitting element shown in FIG. 2, the endportion of the first electrode 31 is formed over the edge portion of thefirst light reflecting layer 41. In a case in which the first electrode31 is extended onto the edge portion of the first light reflecting layer41, an opening portion 31A, for example, an opening portion 31A with adiameter of 5 μm to 50 μm is formed in the first electrode 31 such thatbasic mode light of laser oscillation is absorbed as little as possible.The same applies in the description below. Alternatively, it is possibleto use a configuration in which the first surface 21 a in the roughsurface region 21A is positioned further downwards than the flat surface21B.

Embodiment 2

Embodiment 2 relates to a method of manufacturing a light emittingelement according to the second embodiment of disclosure and to thelight emitting element of the disclosure. Although FIG. 6A shows aschematic partial end face view of the light emitting element ofEmbodiment 2, the configuration and structure of the light emittingelement of Embodiment 2 is substantially the same as the configurationand structure of the light emitting element of Embodiment 1, except thatthe configuration and structure of the first light reflecting layer 41,the first electrode 31 and the periphery thereof are slightly different.Therefore, in the light emitting element of Embodiment 2, theconfiguration and structure of the first light reflecting layer 41, thefirst electrode 31 and the periphery thereof will be exclusivelydescribed.

In the light emitting element of Embodiment 2 shown by the schematicpartial end face view in FIG. 6A, a concavity 21C with a forward taperedside surface 21E is formed on the first surface 21 a of the firstcompound semiconductor layer 21. That is, the bottom surface 21D of theconcavity 21C positioned on the active layer side is smaller than theopening portion 21F position on the first surface 21 a of the firstcompound semiconductor layer 21. The first light reflecting layer 41 isformed on at least the concavity 21C, and the first electrode 31 isformed on at least the first surface 21 a of the first compoundsemiconductor layer 21. The end portion of the first electrode 31 isseparated from the first light reflecting layer 41.

Below, the method of manufacturing a light emitting element ofEmbodiment 2 will be described with reference to FIGS. 13A, 13B, 13C,14A, 14B, 15A, 15B, 16 which are schematic partial end face views of alayered structure body.

Step-200

First, a convexity (mask layer for selective growth) 51 formed from amaterial different from the material that configures the first compoundsemiconductor layer 21 is formed on the substrate for manufacturing alight emitting element 11. Specifically, a patterned convexity 51 formedfrom SiO₂ is formed, based, for example, on an existing method, such asan etch back method, on the substrate for manufacturing a light emittingelement 11 formed from a GaN substrate. The top surface 51A of theconvexity 51 is smaller than the bottom surface 51B of the convexity 51.In this way, it is possible to obtain the structure shown in FIG. 13A.The shape of the convexity 51 is a truncated cone. However, the shape ofthe convexity 51 is not limited thereto.

Step-210

Next, a layered structure body 20 in which a first compoundsemiconductor layer 21 formed from a GaN-based compound semiconductor,which has a first surface 21 a and a second surface 21 b opposing thefirst surface 21 a, an active layer 23 formed from a GaN-based compoundsemiconductor, that contacts the second surface 21 b of the firstcompound semiconductor layer 21, and a second compound semiconductorlayer 22 formed from a GaN-based compound semiconductor, which has afirst surface 22 a and a second surface 22 b opposing the first surface22 a, in which the first surface 22 a contacts the active layer 23 arelayered is formed on the substrate for manufacturing a light emittingelement 11 including the convexity 51. Specifically, it is possible toobtain a layered structure body 20 by forming the first compoundsemiconductor layer 21 formed from n-GaN by lateral direction growthusing a method that causes epitaxial growth in the lateral direction,such as an ELO method, and forming the active layer 23 and the secondcompound semiconductor layer 22 thereupon, based on an epitaxial growthmethod. Then, the current constriction layer 24 having an opening 24A isformed, based on an existing method, on the second surface 22 b of thesecond compound semiconductor layer 22 (refer to FIG. 13B).

Step-220

Thereafter, the second electrode 32 and the second light reflectinglayer 42 formed from a multilayer film are formed on the second surface22 b of the second compound semiconductor layer 22. Specifically, forexample, the second electrode 32 is formed from over the second surface22 b of the second compound semiconductor layer 22 to over the currentconstriction layer 24 based on a lift-off method and the pad electrode33 is further formed from over the second electrode 32 to over thecurrent constriction layer 24 based on an existing method. In this way,it is possible to obtain the structure shown in FIG. 13C. Thereafter,the second light reflecting layer 42 is formed from over the secondelectrode 32 to over the pad electrode 33 based on an existing method.In this way, it is possible to obtain the structure shown in FIG. 14A.

Step-230

Thereafter, the second light reflecting layer 42 is fixed to the supportsubstrate 26 via a bonding layer 25. In this way, it is possible toobtain the structure shown in FIG. 14B.

Step-240

Next, the substrate for manufacturing a light emitting element 11 isremoved, and the first surface 21 a of the first compound semiconductorlayer 21 and the convexity 51 are exposed. Specifically, the thicknessof the substrate for manufacturing a light emitting element 11 isthinned based on a mechanical polishing method, then the remainder ofthe substrate for manufacturing a light emitting element 11 is removedbased on a CMP method. In this way, the first surface 21 a of the firstcompound semiconductor layer 21 and the convexity 51 are exposed, and itis possible to obtain the structure shown in FIG. 15A.

Step-250

Thereafter, the convexity 51 is removed, the first light reflectinglayer 41 formed from a multilayer film is formed on at least that partof the first surface 21 a of the first compound semiconductor layer 21from which the convexity 51 is removed, and the first electrode 31 isformed on the part of the first surface 21 a of the first compoundsemiconductor layer 21 on which the first electrode 31 is to be formed.

Specifically, removal of the convexity 51, formation of the first lightreflecting layer 41 and formation of the first electrode 31 areperformed in that order. That is, first, the convexity 51 formed fromSiO₂ is removed based on an existing method. In this way, it is possibleto obtain the structure shown in FIG. 15B. A concavity 21C with aforward tapered side surface 21E is formed on the first surface 21 a ofthe first compound semiconductor layer 21. That is, the bottom surface21D of the concavity 21C positioned on the active layer side is smallerthan the opening portion 21F positioned on the first surface 21 a of thefirst compound semiconductor layer 21. Next, the first light reflectinglayer 41 is formed at least in the concavity 21C. Specifically, thepatterned first light reflecting layer 41 formed from a multilayer filmis formed, based on an existing method, from the concavity 21C to overthe first surface 21 a of the substrate for manufacturing a lightemitting element 11. In this way, it is possible to obtain the structureshown in FIG. 16. The first light reflecting layer 41 is formed from theinner portion of the concavity 21C to over the first surface 21 a of thefirst compound semiconductor layer 21. The external shape of the firstlight reflecting layer 41 is a circle. Thereafter, the first electrode31 is formed, based on an existing method, on the part of the firstsurface 21 a of the first compound semiconductor layer 21 on which thefirst electrode 31 is to be formed. In this way, it is possible toobtain the light emitting element of Embodiment 2 having the structureshown in FIG. 6A.

Step-260

Thereafter, the light emitting element is separated by performingso-called element separation, and the exposed surface of the sidesurface of the layered structure body is covered with an insulating filmformed from, for example, SiO₂. Thereafter, a terminal or the like forconnecting the first electrode 31 and the pad electrode 33 to anexternal circuit or the like is formed based on an existing method, andthe light emitting element of Embodiment 2 is completed by packaging orsealing.

In the method of manufacturing a light emitting element of Embodiment 2,the substrate for manufacturing a light emitting element is removed in astate in which the convexity (mask layer for selective growth) isformed. Therefore, the convexity functions as one type of stopper whenremoving the substrate for manufacturing a light emitting element, as aresult it is possible to suppress the occurrence of variations in theremoval of the substrate for manufacturing a light emitting element onthe surface of the substrate for manufacturing a light emitting element,and, further, variations in the thickness of the first compoundsemiconductor layer, and it is possible to attain results enablingachievement of uniformity in the length of the resonator and stabilityin the characteristics of the obtained light emitting element.

In the example of the light emitting element described above and shownin FIG. 6A, the end portion of the first electrode 31 is separated fromthe first light reflecting layer 41. Meanwhile, in the example of thelight emitting element shown in FIG. 6B, the end portion of the firstelectrode 31 contacts the first light reflecting layer 41. In theexample of the light emitting element shown in FIG. 7A, the end portionof the first electrode 31 is formed over the edge portion of the firstlight reflecting layer 41.

In Step-250, the part of the first surface 21 a of the first compoundsemiconductor layer 21 on which the first electrode 31 is to be formedmay be etched before forming the first electrode 31 on the first surface21 a of the first compound semiconductor layer 21, and, in this case,the exposed first compound semiconductor layer 21 may be etched based ona reactive ion etching method. Thereby, a rough surface region 21A isformed on the first surface 21 a of the first compound semiconductorlayer 21. The first electrode 31 may be formed on at least the etchedfirst compound semiconductor layer 21. Although schematic partial endface views of the light emitting element obtained in this way are shownin FIGS. 7B, 8A and 8B, in the example of the light emitting elementshown in FIG. 7B, the end portion of the first electrode 31 is separatedfrom the first light reflecting layer 41. Meanwhile, in the example ofthe light emitting element shown in FIG. 8A, the end portion of thefirst electrode 31 contacts the first light reflecting layer 41. In theexample of the light emitting element shown in FIG. 8B, the end portionof the first electrode 31 is formed over the edge portion of the firstlight reflecting layer 41. Since the first electrode 31 is formed on therough surface region 21A, it is possible to suppress a rise in thecontact resistance between the first compound semiconductor layer 21 andthe first electrode 31.

The value of the surface roughness Ra of the first surface 21 a of thefirst compound semiconductor layer 21 in the interface of the firstlight reflecting layer 41 and the first surface 21 a of the firstcompound semiconductor layer 21 is 3×10⁻⁹ m or less, and the value ofthe surface roughness Ra of the first surface 21 a of the first compoundsemiconductor layer 21 on which the first electrode 31 is to be formedexceeds the value of the surface roughness Ra of the first surface 21 aof the first compound semiconductor layer 21 in the interface of thefirst light reflecting layer 41 and the first surface 21 a of the firstcompound semiconductor layer 21.

R₁/R₂≦1 is satisfied, where the contact resistance value of the firstsurface 21 a of the first compound semiconductor layer 21 in theinterface between the first light reflecting layer 41 and the firstsurface 21 a of the first compound semiconductor layer 21 is R₁, and thecontact resistance value in the first surface 21 a of the first compoundsemiconductor layer 21 on which the first electrode 31 is to be formedis R₂.

As the procedure of removing the convexity, forming the first lightreflecting layer, etching the first compound semiconductor layer, andforming the first electrode, it is possible to use the procedures belowin addition to the above procedure.

(1) removal of the convexity, etching of the first compoundsemiconductor layer, formation of the first light reflecting layer,formation of the first electrode

(2) removal of the convexity, etching of the first compoundsemiconductor layer, formation of the first electrode, formation of thefirst light reflecting layer

(3) etching of the first compound semiconductor layer, removal of theconvexity, formation of the first light reflecting layer, formation ofthe first electrode

(4) etching of the first compound semiconductor layer, removal of theconvexity, formation of the first electrode, formation of the firstlight reflecting layer

(5) etching of the first compound semiconductor layer, formation of thefirst electrode, removal of the convexity, formation of the first lightreflecting layer

In the example of the light emitting element shown in FIGS. 7B, 8A and8B, although the first surface 21 a of the first compound semiconductorlayer 21 is etched so that the side surface of the first lightreflecting layer 41 and the side surface of the rough surface region 21Aof the first surface 21 a of the first compound semiconductor layer 21match, the side surface of the rough surface region 21A of the firstsurface 21 a of the first compound semiconductor layer 21 may be formedfurther to the outside than the side surface of the first lightreflecting layer 41, as shown in FIGS. 9A, 9B, 10A, and 10B. In theexample of the light emitting element shown in FIGS. 9A and 9B, the endportion of the first electrode 31 is separated from the first lightreflecting layer 41. In the example of a light emitting element shown inFIG. 9A, the end portion of the first electrode 31 is separated from theside surface of the rough surface region 21A, and in the example of alight emitting element shown in FIG. 9B, the end portion of the firstelectrode 31 contacts the side surface of the rough surface region 21A.In the example of the light emitting element shown in FIG. 10A, the endportion of the first electrode 31 contacts the first light reflectinglayer 41. In the example of the light emitting element shown in FIG.10B, the end portion of the first electrode 31 is formed over the edgeportion of the first light reflecting layer 41. In the light emittingelement shown in FIGS. 9A, 9B, 10A, and 10B, a protrusion part 21G ofthe first compound semiconductor layer is present between the firstlight reflecting layer 41 and the first electrode 31.

In the example of a light emitting element shown in FIGS. 11A, 11B, 12A,and 12B, the first light reflecting layer 41 extends on the firstelectrode 31. In the example of a light emitting element shown in FIG.11A, the first electrode 31 is provided separated from the openingportion 21F positioned on the first surface 21 a of the first compoundsemiconductor layer 21, and in the example of a light emitting elementshown in FIG. 11B, the first electrode 31 is provided contacting theopening portion 21F. Meanwhile, in the example of a light emittingelement shown in FIGS. 12A and 12B, the first electrode 31 is providedon the rough surface region 21A, in the example of a light emittingelement shown in FIG. 12A, the end portion of the first electrode 31 isseparated from the side surface of the rough surface region 21A, and inthe example of a light emitting element shown in FIG. 12B, the endportion of the first electrode 31 contacts the side surface of the roughsurface region 21A.

Embodiment 3

As described above, on the substrate for manufacturing a light emittingelement 11 on which the first light reflecting layer 41 or the convexity51 is formed, when the first compound semiconductor layer 21 is formedusing horizontal growth using a method in which epitaxial growth iscaused in the horizontal direction, such as an epitaxial lateralovergrowth (ELO) method, if the first compound semiconductor layer 21that is epitaxially grown from the edge portion of the first lightreflecting layer 41 or the convexity 51 towards the center portion ofthe first light reflecting layer 41 or the convexity 51 meet, there arecases in which numerous crystal defects occur in the meeting part.

In the light emitting element of Embodiment 3 or in the method ofmanufacturing a light emitting element of Embodiment 3, the areacentroid of the second light reflecting layer 42 is not present on thenormal line LN1 with respect to the first light reflecting layer 41passing through area centroid of the first light reflecting layer 41, asshown in FIG. 17 by the modification example of the light emittingelement shown in FIG. 1A, and in FIG. 18 by the modification example ofthe light emitting element shown in FIG. 6A. Alternatively, the areacentroid of the active layer 23 is not present on the normal line LN1with respect to the first light reflecting layer 41 that passes throughthe area centroid of the first light reflecting layer 41. The normalline with respect to the second light reflecting layer 42 that passesthrough the area centroid of the second light reflecting layer 42matches the normal line with respect to the active layer 23 that passesthrough the area centroid of the active layer 23, and this line isindicated by “LN2”. Needless to say, it is possible to adopt theconfiguration and structure of a light emitting element of Embodiment 3with respect to the light emitting element shown in FIGS. 1B, 2, 6B, 7A,7B, 8A, 8B, 9A, 9B, 10A, 10B, 11A, 11B, 12A, and 12B. Other than theabove points, since configuration and structure of the light emittingelement of Embodiment 3 are the same as the configuration and structureof the light emitting element of Embodiments 1 and 2, a detaileddescription will not be made.

S₃>S₄ is satisfied, where the area of a part of the first lightreflecting layer 41 that contacts the first surface 21 a of the firstcompound semiconductor layer 21 (part of the first light reflectinglayer 41 opposing the second light reflecting layer 42) that configuresthe element region is S₃, and the area of a part of the second lightreflecting layer 42 opposing the second surface 22 b of the secondcompound semiconductor layer 22 (part of the second light reflectinglayer 42 opposing the first light reflecting layer 41) that configuresthe element region is S₄.

In Embodiment 3, the meeting part in which numerous crystal defects arepresent (specifically, positioning on the normal line LN1 or in thevicinity thereof) is not positioned in the center portion of the elementregion, and the occurrence of a negative influence on thecharacteristics of the light emitting element is eliminated, or thenegative influence on the characteristics of the light emitting elementis reduced.

Above, although the present disclosure has been described based onpreferred examples, the present disclosure is not limited to theseexamples. The configuration and structure of the light emitting elementdescribed in the examples are examples and may be changed, asappropriate. It is also possible to change the method of manufacturing alight emitting element of the examples, as appropriate. It is possibleto make a surface-emitting laser element that emits light from the topsurface of the second compound semiconductor layer via the second lightreflecting layer by suitably selecting the bonding layer and supportsubstrate, according to the circumstances. It is possible to use asurface-emitting laser element that emits light from the top surface ofthe second compound semiconductor layer via the second light reflectinglayer, also by making the light emitting element obtained in the stepsup to Step-130 into a completed product. Alternatively, in Step-160 andStep-260, by removing the support substrate after the first lightreflecting layer and the first electrode are formed, it is possible forthe surface-emitting laser element that emits light from the top surfacethe second compound semiconductor layer via the second light reflectinglayer to be completed, or after Step-160 and Step-260, by fixing thefirst light reflecting layer to the second support substrate, andthereafter the second light reflecting layer being exposed by removingthe support substrate, it is possible for the surface-emitting laserelement that emits light from the top surface of the second compoundsemiconductor layer via the second light reflecting layer to becompleted.

The present disclosure may take the configurations as below.

[A01] Method of Manufacturing Light Emitting Element

First Embodiment

A method of manufacturing a light emitting element includes,sequentially (a) forming a first light reflecting layer having a convexshape formed from a multilayer film on a substrate for manufacturing alight emitting element; (b) forming a layered structure body by layeringa first compound semiconductor layer formed from a GaN-based compoundsemiconductor, which has a first surface and a second surface opposingthe first surface, an active layer formed from a GaN-based compoundsemiconductor, which contacts the second surface of the first compoundsemiconductor layer, and a second compound semiconductor layer formedfrom a GaN-based compound semiconductor, which has a first surface and asecond surface opposing the first surface, in which the first surfacecontacts the active layer on the substrate for manufacturing a lightemitting element that includes the first light reflecting layer; (c)forming, on the second surface of the second compound semiconductorlayer, a second electrode and a second light reflecting layer formedfrom a multilayer film; (d) fixing the second light reflecting layer toa support substrate; (e) removing the substrate for manufacturing alight emitting element, and exposing the first surface of the firstcompound semiconductor layer and the first light reflecting layer; (f)etching the first surface of the first compound semiconductor layer; and(g) forming a first electrode on at least the etched first surface ofthe first compound semiconductor layer.

[A02] The method of manufacturing a light emitting element according to[A01], in which exposure of the first surface of the first compoundsemiconductor layer and the first light reflecting layer in (e) isperformed based on a chemical/mechanical polishing method.

[A03] The method of manufacturing a light emitting element according to[A01] or [A02], in which a part of the first surface of the firstcompound semiconductor layer on which the first electrode is to beformed is etched based on a reactive ion etching method.

[A04] The method of manufacturing a light emitting element according toany one of [A01] to [A03], in which an area centroid of the second lightreflecting layer is not present on a normal line with respect to thefirst light reflecting layer that passes through the area centroid ofthe first light reflecting layer.

[A05] The method of manufacturing a light emitting element according toany one of [A01] to [A04], in which an area centroid of the active layeris not present on a normal line with respect to the first lightreflecting layer that passes through the area centroid of the firstlight reflecting layer.

[A06] A method of manufacturing a light emitting element according toany one of [A01] to [A05] in which the first light reflecting layer andthe first electrode are in contact.

[A07] The method of manufacturing a light emitting element according toany one of [A01] and [A05] in which the first light reflecting layer andthe first electrode are separated, and the separation distance is within1 mm.

[A08] The method of manufacturing a light emitting element according toany one of [A01] and [A07], in which the distance from the first lightreflecting layer to the second light reflecting layer is 0.15 μm or moreand 50 μm or less.

[A09] The method of manufacturing a light emitting element according toany one of [A01] to [A08], in which light generated in the active layeris emitted to the outside via the first light reflecting layer.

[A10] The method of manufacturing a light emitting element according[A09], in which S₁>S₂ is satisfied, where the area of a part of thefirst light reflecting layer that contacts the first surface of thefirst compound semiconductor layer is S₁, and the area of a part of thesecond light reflecting layer opposing the second surface of the secondcompound semiconductor layer is S₂.

[A11] The method of manufacturing a light emitting element according toany one of [A01] to [A10], in which a value of the surface roughness Raof a part of the first surface of the first compound semiconductor layerthat contacts the first light reflecting layer is 3×10⁻⁹ m or less, andthe value of the surface roughness Ra of a part of the first surface ofthe first compound semiconductor layer on which the first electrode isformed exceeds the value of the surface roughness Ra of a part of thefirst surface of the first compound semiconductor layer that contactsthe first light reflecting layer.

[A12] The method of manufacturing a light emitting element according toany one of [A01] to [A11], in which R₂/R₁≦1 is satisfied, where thecontact resistance value of a part of the first surface of the firstcompound semiconductor layer that contacts the first light reflectinglayer is R₁, and the contact resistance value of a part of the firstsurface of the first compound semiconductor layer on which the firstelectrode is formed is R₂.

[A13] The method of manufacturing a light emitting element according toany one of [A01] to [A12], in which the first electrode is formed from ametal or an alloy.

[A14] The method of manufacturing a light emitting element according toany one of [A01] to [A13], in which the second electrode is formed froma transparent conductive material.

[A15] The method of manufacturing a light emitting element according toany one of [A01] to [A14], in which the light emitting element is formedfrom a surface-emitting laser element.

[B01] Method of Manufacturing Light Emitting Element

Second Embodiment

A method of manufacturing a light emitting element includes,sequentially, (a) forming a convexity formed from a material differentfrom a material that configures a first compound semiconductor layer ona substrate for manufacturing a light emitting element; (b) forming alayered structure body by layering a first compound semiconductor layerformed from a GaN-based compound semiconductor, which has a firstsurface and a second surface opposing the first surface, an active layerformed from a GaN-based compound semiconductor, which contacts thesecond surface of the first compound semiconductor layer, and a secondcompound semiconductor layer formed from a GaN-based compoundsemiconductor, which has a first surface and a second surface opposingthe first surface, in which the first surface contacts the active layeron the substrate for manufacturing a light emitting element thatincludes the convexity; (c) forming, on the second surface of the secondcompound semiconductor layer, a second electrode and a second lightreflecting layer formed from a multilayer film; (d) fixing the secondlight reflecting layer to a support substrate; (e) removing thesubstrate for manufacturing a light emitting element, and exposing thefirst surface of the first compound semiconductor layer and theconvexity; and (f) removing the convexity, forming a first lightreflecting layer formed from a multilayer film on at least a part of thefirst surface on the first compound semiconductor layer from which theconvexity is removed, and forming a first electrode on at least a partof the first surface of the first compound semiconductor layer on whichat least the first electrode is to be formed.

[B02] The method of manufacturing a light emitting element according to[B01], in which exposure of the first surface of the first compoundsemiconductor layer and the convexity in (e) is performed based on achemical/mechanical polishing method.

[B03] The method of manufacturing a light emitting element according to[B01] or [B02], in which a part of the first surface of the firstcompound semiconductor layer on which the first electrode is to beformed is etched before the first electrode is formed on the firstsurface of the first compound semiconductor layer in (f).

[B04] The method of manufacturing a light emitting element according to[B03], in which a part of the first surface of the first compoundsemiconductor layer on which the first electrode is to be formed isetched based on a reactive ion etching method.

[B05] The method of manufacturing a light emitting element according toany one of [B01] to [B04], in which the convexity formed in step (a) hasa top surface smaller than a bottom surface.

[B06] The method of manufacturing a light emitting element according toany one of [B01] to [B05], in which an area centroid of the second lightreflecting layer is not present on a normal line with respect to thefirst light reflecting layer that passes through the area centroid ofthe first light reflecting layer.

[B07] The method of manufacturing a light emitting element according toany one of [B01] to [B06], in which an area centroid of the active layeris not present on a normal line with respect to the first lightreflecting layer that passes through the area centroid of the firstlight reflecting layer.

[B08] The method of manufacturing a light emitting element according toany one of [B01] to [B07] in which the first light reflecting layer andthe first electrode are in contact.

[B09] The method of manufacturing a light emitting element according toany one of [B01] to [B07] in which the first light reflecting layer andthe first electrode are separated, and the separation distance is within1 mm.

[B10] The method of manufacturing a light emitting element according to[B09], in which a protrusion part of the first compound semiconductorlayer is present between the first light reflecting layer and the firstelectrode.

[B11] The method of manufacturing a light emitting element according toany one of [B01] and [B10], in which the distance from the first lightreflecting layer to the second light reflecting layer is 0.15 μm or moreand 50 μm or less.

[B12] The method of manufacturing a light emitting element according toany one of [B01] to [B11], in which light generated in the active layeris emitted to the outside via the first light reflecting layer.

[B13] The method of manufacturing a light emitting element according[B12], in which S₁>S₂ is satisfied, where the area of a part of thefirst light reflecting layer that contacts the first surface of thefirst compound semiconductor layer is S₁, and the area of a part of thesecond light reflecting layer opposing the second surface of the secondcompound semiconductor layer is S₂.

[B14] The method of manufacturing of a light emitting element accordingto any one of [B01] to [B14], in which a value of the surface roughnessRa of a part of the first surface of the first compound semiconductorlayer that contacts the first light reflecting layer is 3×10⁻⁹ m orless, and the value of the surface roughness Ra of a part of the firstsurface of the first compound semiconductor layer on which the firstelectrode is formed exceeds the value of the surface roughness Ra of apart of the first surface of the first compound semiconductor layer thatcontacts the first light reflecting layer.

[B15] The method of manufacturing a light emitting element according toany one of [B01] to [B14], in which R₂/R₁≦1 is satisfied, where thecontact resistance value of a part of the first surface of the firstcompound semiconductor layer that contacts the first light reflectinglayer is R₁, and the contact resistance value of a part of the firstsurface of the first compound semiconductor layer on which the firstelectrode is formed is R₂.

[B16] The method of manufacturing a light emitting element according toany one of [B01] to [B15], in which the first electrode is formed from ametal or an alloy.

[B17] The method of manufacturing a light emitting element according toany one of [B01] to [B16], in which the second electrode is formed froma transparent conductive material.

[B18] The method of manufacturing a light emitting element according toany one of [B01] to [B17], in which the light emitting element is formedfrom a surface-emitting laser element.

[C01] Light Emitting Element

A light emitting element includes (A) a layered structure body formed bylayering a first compound semiconductor layer formed from a GaN-basedcompound semiconductor, which has a first surface and a second surfaceopposing the first surface, an active layer formed from a GaN-basedcompound semiconductor, which contacts the second surface of the firstcompound semiconductor layer, and a second compound semiconductor layerformed from a GaN-based compound semiconductor, which has a firstsurface and a second surface opposing the first surface, and in whichthe first surface contacts the active layer; (B) a first electrode and afirst light reflecting layer; and (C) a second electrode and a secondlight reflecting layer formed from a multi layer film formed on thesecond surface of the second compound semiconductor layer, in which aconcavity with a forward tapered side surface is formed on the firstsurface of the first compound semiconductor layer, the first lightreflecting layer is formed on at least the concavity, and the firstelectrode is formed on at least the first surface of the first compoundsemiconductor layer.

[C02] The light emitting element according to [C01], in which an areacentroid of the second light reflecting layer is not present on a normalline with respect to the first light reflecting layer that passesthrough the area centroid of the first light reflecting layer.

[C03] The light emitting element according to [C01] or [C02], in whichan area centroid of the active layer is not present on a normal linewith respect to the first light reflecting layer that passes through thearea centroid of the first light reflecting layer.

[C04] The light emitting element according to any one of [C01] to [C03],in which light generated in the active layer is emitted to the outsidevia the first light reflecting layer.

[C05] The light emitting element according [C04], in which S₁>S₂ issatisfied, where the area of a part of the first light reflecting layerthat contacts the first surface of the first compound semiconductorlayer is S₁, and the area of a part of the second light reflecting layeropposing the second surface of the second compound semiconductor layeris S₂.

[C06] The light emitting element according to any one of [C01] to [C05],in which a value of the surface roughness Ra of a part of the firstsurface of the first compound semiconductor layer that contacts thefirst light reflecting layer is 3×10⁻⁹ m or less, and the value of thesurface roughness Ra of a part of the first surface of the firstcompound semiconductor layer on which the first electrode is formedexceeds the value of the surface roughness Ra of a part of the firstsurface of the first compound semiconductor layer that contacts thefirst light reflecting layer.

[C07] The light emitting element according to any one of [C01] to [C06],in which R₂/R₁≦1 is satisfied, where the contact resistance value of apart of the first surface of the first compound semiconductor layer thatcontacts the first light reflecting layer is R₁, and the contactresistance value of a part of the first surface of the first compoundsemiconductor layer on which the first electrode is formed is R₂.

[C08] The light emitting element according to any one of [C01] to [C07],in which the first light reflecting layer and the first electrode are incontact.

[C09] The light emitting element according to any one of [C01] and [C07]in which the first light reflecting layer and the first electrode areseparated, and the separation distance is within 1 mm.

[C10] The light emitting element according to [C09], in which aprotrusion part of the first compound semiconductor layer is presentbetween the first light reflecting layer and the first electrode.

[C11] The light emitting element according to any one of [C01] and[C10], in which the distance from the first light reflecting layer andthe second light reflecting layer is 0.15 μm or more and 50 μm or less.

[C12] The light emitting element according to any one of [C01] to [C11],in which the second light reflecting layer is fixed to the supportsubstrate.

[C13] The light emitting element according to any one of [C01] to [C12],in which the first electrode is formed from a metal or an alloy.

[C14] The light emitting element according to any one of [C01] to [C13],in which the second electrode is formed from a transparent conductivematerial.

[C15] The light emitting element according to any one of [C01] to [C14],in which the light emitting element is formed from a surface-emittinglaser element.

It should be understood by those skilled in the art that variousmodifications, combinations, sub-combinations and alterations may occurdepending on design requirements and other factors insofar as they arewithin the scope of the appended claims or the equivalents thereof.

What is claimed is:
 1. A method of manufacturing a light emittingelement comprising: forming a convexity formed from a material differentfrom a material that configures a first compound semiconductor layer ona substrate for manufacturing a light emitting element; forming alayered structure body by layering the first compound semiconductorlayer formed from a GaN-based compound semiconductor, which has a firstsurface and a second surface opposing the first surface, an active layerformed from a GaN-based compound semiconductor, which contacts thesecond surface of the first compound semiconductor layer, and a secondcompound semiconductor layer formed from a GaN-based compoundsemiconductor, which has a first surface and a second surface opposingthe first surface, and in which the first surface contacts the activelayer on the substrate for manufacturing a light emitting element thatincludes the convexity; forming, on the second surface of the secondcompound semiconductor layer, a second electrode and a second lightreflecting layer formed from a multilayer film; fixing the second lightreflecting layer to a support substrate; removing the substrate formanufacturing a light emitting element, and exposing the first surfaceof the first compound semiconductor layer and the convexity; andremoving the convexity, forming a first light reflecting layer formedfrom a multilayer film on at least a part of the first surface on thefirst compound semiconductor layer from which the convexity is removed,and forming a first electrode on at least a part of the first surface ofthe first compound semiconductor layer on which the first electrode isto be formed.
 2. The method of manufacturing a light emitting elementaccording to claim 1, wherein exposure of the first surface of the firstcompound semiconductor layer and the convexity is performed based on achemical/mechanical polishing method.
 3. The method of manufacturing alight emitting element according to claim 1, wherein a part of the firstsurface of the first compound semiconductor layer on which the firstelectrode is to be formed is etched before the first electrode is formedon the first surface of the first compound semiconductor layer.
 4. Themethod of manufacturing a light emitting element according to claim 3,wherein the part of the first surface of the first compoundsemiconductor layer on which the first electrode is to be formed isetched based on a reactive ion etching method.
 5. The method ofmanufacturing a light emitting element according to claim 1, wherein theconvexity includes a top surface smaller than a bottom surface.
 6. Themethod of manufacturing a light emitting element according to claim 1,wherein an area centroid of the second light reflecting layer is notpresent on a normal line with respect to the first light reflectinglayer that passes through the area centroid of the first lightreflecting layer.
 7. The method of manufacturing a light emittingelement according to claim 1, wherein an area centroid of the activelayer is not present on a normal line with respect to the first lightreflecting layer that passes through the area centroid of the firstlight reflecting layer.